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This is a work in progress. Feel free to edit as you please.
The Roraima pollen paradox is the supposed contradiction posed by pollen found in rock samples collected from Mount Roraima.[wp] Radiometric dating of those rocks places them in the Pre-Cambrian (ca. 540 Mya), hundreds of millions of years before pollen-bearing plants arose (ca. 245 Mya).
The only source of direct evidence on the paradox is a 49-year-old study by R.M. Stainforth.[1]
The pollen has been cited by many creationists as evidence of the falsity of either evolutionary timetables or radiometric dating.[2][3]
[edit] What's the paradox?
[edit] Contamination
[edit] Could pollen get in?
Some of the scientists suggested such a thing:[1]
| As to interpretation of the significance of the fossil pollen and spores, two sharply divided opinions have been expressed. The writers make no attempt to adjudicate, but state the two concepts impartially. One group adopts the attitude that the radiometric dating of dolerites and a hornfels within the Roraima Formation as Precambrian is beyond dispute, hence the pollen (and spores) must have entered as secondary contamination. The improbability that pollen could withstand the baking process, which converted shale to hornfels, is adduced as further evidence that the pollen must be allochthonous. The absence of macroscopic plant remains in the Roraima Formation is also noted, despite its assumed continental (?fluviatile) origin. It is admitted that entry of the pollen into its present site defies simple explanation, though some form of washing in by meteoric waters in the geological past via joints in the overlying sandstone seems the most probable cause.
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Their three major points were:
- Pollen probably can't withstand the intensely hot baking process that converts shale to hornfels
- There were no macroscopic plant remains, even though it supposedly came from a river
- Breaks in the sandstone may have allowed pollen to enter
Although they were opposed:
| The second group holds that by no conceivable physical means could the pollen (and spores) have entered the metamorphosed sediments from the outside. They are dense impermeable rocks compressed by an overburden of hundreds of feet of the overlying Roraima sandstones. The undercutting at Cerro Venamo suggests that the cliff has been steadily retreating, hence the face which was sampled must have been deep within the formation until quite recent times. The Roraima sandstones are quartzitic, of low permeability, hence carriage of extraneous pollen through them by percolating water seems highly improbable. Even if this process could occur, entry of such pollen and spores into the nonporous hornfels lacks an explanation. Furthermore, if plausibility of this process be granted, it would have been operative for a long period, and a mixed suite of spores and pollen should be expected. In counter‑argument against the first group, it is claimed that the assertion that pollen and spores cannot withstand anaerobic baking of their parent shales has never been tested experimentally.
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Their five major points were:
- Pollen couldn't enter through breaks in hundreds of feet of sandstone
- Water penetration is unlikely in the quartzitic sandstone
- Water penetration is extremely unlikely in the hornfels
- If such a process occurred, many years of pollen should be recorded
- Pollen can withstand anaerobic baking
[edit] Quotemining the article
As evidence against contamination, creationists will cite specifically one line of the original article:
| Utmost care was taken to avoid any possibility of superficial contamination.
|
However, the fuller quote reads:[1]
| This discovery of pollen and spores in a formation of supposed Precambrian age was so remarkable that a reconnaissance expedition of qualified geologists was organized to verify the facts of the case. During April, 1964, with the assistance of personnel and vehicles of the Ministerio de Minas e Hidrocarburos, the locality was visited by a party which included N. Benain, P. J. Bermúdez, A. Espejo, U. Fournier, A. Menéndez, J. A. Sulek and F. Wright. They confirmed the salient facts as recorded by Dunsterville. The shale‑like beds, being less competent, had eroded away below the massive Roraima sandstone, leaving an undercut extending 10‑12 ft. inwards at the base of the cliff. The original samples were loose, weathered fragments from the talus slope below. New samples of unweathered rock were collected from the face of the undercut. On their return to Caracas, the three palynologists made independent investigations of the new samples. Utmost care was taken to avoid any possibility of superficial contamination. The rock cleaves along finely laminated bedding planes which are coated with limonite. Every effort was made to avoid these planes and some of the pieces processed were the central nubs left after chipping away the external parts of large blocks of the rock, which was dense enough to sound when struck with a hammer. Nevertheless, microfossils of the same type as before were recovered.
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This context makes it clear that "superficial contamination" refers to the extracts being contaminated after the geologists had taken them, not being contaminated during the entirety of their geological formation.
[edit] What kind of pollen is it?
Fournier:[1]
| G. Fournier, by utilizing the herbarium of J. Steyermark, was able to compare the recent pollen of the area with the assemblage in the rocks, and has stated that they are not the same. The first opinion of Fournier was that the pollen showed Cretaceous affinities, but closer study has led to preference for a Tertiary age.
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Nijssen:[1]
| L. Nijssen regards the best assemblage, from a Paruima sample, as not older than Eocene and quite possibly post‑Eocene.
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Funkhauser:[1]
| J. W. Funkhouser (Bogotá) considers the pollen indigenous to the samples he processed but claims an age no older than Miocene, and probably younger; he notes similarities to the flora of the Mesa Formation (Pliocene‑ ?Pleistocene) of Colombia, presence of pollen of the Compositae, and an uncompressed preservation highly unusual except in young sediments.
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van der Hammen:[1]
| T. van der Hammen (Leiden) recognizes a mixture of Mesozoic and Cenozoic elements, but suspects that they represent foreign material concentrated along cleavage planes as, after cleaning fragments ultrasonically, he found the matrix practically barren.
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[edit] Censorship
Emil Silvestru of Creation.com states:[2]
| In the 1940s and 1950s the discovery of fossils outside the accepted evolutionary position in biostratigraphy was usually honestly reported and discussed. In the following years, examples that could not be explained were simply ignored, never being mentioned again. Although this paper will only deal with the South American fossils and sediments, I would like to also mention that it does not represent the only such case: the discovery of vascular wood and six-legged, composite-eyed insects in the Precambrian salt deposits of the Salt Range in Pakistan. After many unsuccessful and well-documented efforts to explain the discoveries away, a veil of silence covered them so that the most recent available to the Salt Range does not mention any fossil finds. [....] It is fair to say that nothing much was heard of or done about this discovery until creationists started referencing it in the 1990s. One would have expected Nature to encourage and publish new research aiming to eliminate the paradox, but nothing seems to have happened.
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Silvestru dabbles in conspiracy and persecution. It's entirely possible that nobody's researched the issue because nobody knew about, cared about, or had resources to act on the pollen. Silvestru instead implies that evolutionists have somehow organizedly silenced their opposition, without any evidence to support this assertion.
[edit] Conclusions
Silvestru quotes Stainforth in his conclusion:
| Stainforth’s conclusion to his Nature article has become a staple to many creationists: “As stated, we offer no solution to the paradox. It is clear, however, that the botanist Dunsterville in his hunt for rare orchids stumbled on a highly intriguing geological problem.”
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Silvestru claims this as a victory for YEC. However, it's hard to accept a scientific "dunno what happened here" as strong evidence for YEC.
[edit] Dumping area
Sandstone, or abandoned Imperial AT-AT Walker? You decide...
| It needs to be stated that petrological investigation of the rocks which yielded pollen and spores showed them to be highly metamorphosed, even though in hand specimens they somewhat resembled indurated shales (Fig. 1). J. M. Bowen (Cia. Shell do Venezuela) described the samples from both Cerro Venamo and Paruima as true hornfelses in the cordierite-andalusite range, based on thin-section investigations (Fig. 2). Prof. H. H. Hess (Princeton University) confirmed this on the basis of X-ray diffraction investigations, and described the rock as a fairly typical hornfels, largely muscovite plus a little quartz, clay minerals apparently absent, and no chlorite noted. The samples from Paruima were rather more highly metamorphosed, as shown by the presence of biotite.
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| As regards the radiometric dating, there is a disquieting overlap between stated ages of the Roraima Formation and the underlying basement rocks. The latter suffered complex deformation and vulcanism, and were then deeply peneplaned before being covered by thousands of feet of Roraima sandstones, and only after these prolonged events were the dolerites intruded, on which age‑determination of the Roraima has been based. If the radiometric technique is valid there should be a long and clear‑cut time‑gap between ages assigned to the basement rocks and to the Roraima beds. Such a gap does not exist in the experimental results published, but this discrepancy is glossed over in the latest summary of radiometric dating in British Guiana.
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Fig. 1. Hand specimen of ‘shale’ from Cerro Venamo locality, showing bedding plane parallel to bottom edge, and diagonal cleavage. Natural size.
[1]
Fig. 2. Paruima hornfels (crossed nicols); large crystals are all cordierite in micaceous ground, with original fine quartz banding still preserved; biotite may be seen to right of centre of field. (x 150)
[1]
Figure 3: REGIONAL CROSS SECTION THROUGH THE RORAIMA FORMATION IN WESTERN BRITISH GUIANA (showing positions of polliniferous beds and of samples determined radionmetrically as Precambrian).
[1]
[edit] Known useful info
"the samples were taken from an area formed by the collapse of shale, allowing quite some permeability. "The shale‑like beds ... had eroded ... below the ... Roraima sandstone, leaving an undercut ... at the base of the cliff. .... New samples ... were collected from the face of the undercut.""
"Further, hornfels are created often by compression and heating of shale and other high-permeability rocks [2][3][4][5], which makes it entirely possible that the pollen permeated the shale before being compressed. The permeability of shale, in fact, aids my case."
"the world is a big place" it's bound to happen somewhere
"Further, the rocks in question were undergoing quite some metamorphism and movement,[6] as evidenced by their high temperature. This means that cracks could easily have formed and pollen entered said rock by itself or other rocks with pollen in them have been pushed into the hornfel, "
"Creationists need to explain why we don't find, say, bunnies, or humans, or flowering plants below the Cretacious layer. Because in the Biblical Creationist world, it all kind of happened all at once."
| …pollen was not noted in thin section. …and that temperatures of 400 to 800 degrees C would have been involved in the formation of the rock. Both of these observations support the likelihood of later “contamination” of the rocks with pollen."
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| Mr. Fournier did not challenge the Precambrian radiometric dating of certain sills which cut the Roraima Formation, but suggested that the formation has accumulated gradually through the whole geologic time, and that careful correlations would show that the polleniferous beds belonged to a higher level.
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| How about this: In Venezuelax, in Guyana, in Kashmir, hell in the Grand Canyon, spores of ferns and pollen from flowering plants are found in Cambrian rocks supposedly deposited before flowering plants evolved.
Please see:R. M. Stainforth, �Occurrence of Pollen and Spores in the Roraima Formation of Venezuela and British Guiana,� Nature, Vol. 210, 16 April 1966, pp. 292�294, and A. K. Ghosh and A. Bose, �Spores and Tracheids from the Cambrian of Kashmir,� Nature, Vol. 169, 21 June 1952, pp. 1056�1057.
Apparently the rocks in all cases were exposed to surficial conditions where the microscopic debris could penetrate. When pollen coated the material it could then infiltrate rock pores, carried by water (i.e. cross-contamination). Again, what types of rock? It is interesting to note that Cambrian rock is predominantly sandstone, generally quite porous.
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| "The second contention is another example of flinging mud at the wall and hoping something sticks. For finding pollen microfossils in rocks absent of larger plant remains is neither unusual nor reason to assume contamination, as Berkley's Museum of Paleontology can attest: “Indeed, some very thick rock layers are made entirely of microfossils.”(5) In fact, according to London's Global University's Department of Earth Sciences,“spores and pollen are normally retrieved from their host sediments as disjunct entities, separate from the original parent plant”.(6) So finding pollen fossils without fossils of it's host plant is actually common."
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| organic-walled microfossils may survive significant metamorphic heating
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| The presence of oxygen has noticeably damaging effects on the acritarchs within the heating system as no acritarchs were recovered from oxicpreparation capsules heated for greater than 5 days, while morphologies of heated, anoxic-preparation acritarchs are retained for up to at least 250 days;
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| As alluded to above, metamorphic shearing and heating are generally perceived as destructive processes in fossil preservation and thus highly metamorphosed rocks have not been a target of paleontological exploration. [....] The effects of pressure and directional shearing on fossil preservation have not been investigated in our experiments.
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As Mr. Stainforth writes:[4]
| This suite indicates baking of the original shales to temperatures of 400-800°C.
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However:
| To experimentally examine whether organic-walled vesicles graphitize and retain biological morphology during metamorphic heating, Mesoproterozoic (~1300 Ma) Ruyang Group rock samples containing dense populations of acritarchs (e.g. Dictyosphaera delicata and Shiuyousphaeridium macroreticulatum) have been heated to 500°C (± 2.5°C) in gold capsules (prepared in both oxic and anoxic conditions) under 1 atm isotropic pressure for varying lengths of time, ranging from 1 day to 250 days.
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Allen Roy:
| [N]o one familiar with pollen should be surprised that pollen is found in surface exposed rocks. There is a veritible rain of pollen on everything. It is caught in rain water and transported down into the crevices in the rocks. So regardless of finding modern pollen in surficial rocks, it may not have been there from time immemorial. It may be a recent addition to the rock a modern contaminant. You don't even have to have a pine tree anywhere near you to have pine pollen falling on you. Wind and water disperse the pollen quite effectively. A palynologist friend of mine has written that he finds modern pine pollen in his cretaceous preparations all the time. How can one differentiate between modern and ancient pollen? My palynologist friend sets out 3 criteria for determining the contemporaneity of the pollen with the rock: 1 The first criteria is color. As organic matter ages, it becomes darker. This is especially true as the rock is buried and the temperature rises. If the pollen is clear or very light yellow then they are modern introduced forms. Remember that the Hakatai shale has been buried by more than 7,000 feet before the erosion began removing the sediment. At such a depth of burial the temperature would be approximately 190 deg F and the organic matter would turn brown. 2. One must demonstrate that the Hakatai shale is not so thermally mature (cooked) that nothing organic could have survived. With all the volcanism, this rock is cooked. I looked up in the Lexicon of Geologic names of the United States, and found that the Hakatai contains diabase volcanic sills. This means that the lava intruded into the Hakatai. 3. The pollen grains should be flattened. My friend says that the pollen grains are compressed when buried in sedimentary rocks. This is especially true if the burial is as deep as the Hakatai was buried.
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Arthur Chadwick, talking about supposed Precambrian pollen in the Grand Canyon:[5]
| [T]he conclusion that these findings support the concept of Precambrian higher plants is a non sequitur until all cause for concern regarding modern contamination has been eliminated.
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| A total of fifty samples from the same strata which Burdick had studied were processed. All slides were completely scanned. No single example of an authentic pollen grain was obtained from any of these samples. In fact, the slides produced from the Hakatai Formation were in most cases completely free from any material of biologic origin, modern or fossil.
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| No rigorous attempt was apparently made by Burdick to evaluate personally the modern pollen rain in the Grand Canyon. A single sample of soil from near one of the modern collecting sites could have completely satisfied Burdick as to the source of most of the grains he has reported. A typical analysis of a site near where Burdick collected his Hakatai samples yielded the following profile: bisaccate pollen (conifers) 30%; juniper 12%; ephedra 16%; various species of angiosperms (42%) (Siegels,1971). Although the poor quality of the photographs in the plates of Burdick's first paper makes definite assignments impossible, one can approximate the composition of the flora he reports. Of the grains identifiable as pollen or spores in the two papers by Burdick (n=18), 7 or 37% are bisaccates, 2 or 11% are possibly juniper. Ephedra pollen constitute 11% and angiosperms and unassignable grains 34%. Thus even with this small sample size, Burdick's grains approximate the modern pollen rain found in surface sample in the area of the Grand Canyon where he collected his samples.
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| More difficulties are created than are solved by Burdick's report since it would require the explanation of the accumulation of all the Upper Precambrian sediments (10,000 ft.), their lithification and subsequent erosion before the first additional fossil forms were buried. Add to this the picture the many thousands of macerations of lower Paleozoic and Precambrian rocks which have been carried out in scores of laboratories around the world which have not supported Burdick's claims. There is a general absence of evidence for flowering plants below the middle Cretaceous. It is a responsibility and challenge to the creationists to develop a model of earth history which explains the absence. [....] In our hands, application of the cardinal principle of the scientific method - reproducibility - has failed to authenticate his record. thus the hypothesis that the grains are authentic examples of Precambrian pollen can only be treated with incredulity at present, even among creationists.
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| The utmost care has been taken to eliminate any possibility of superficial contamination, but even the small nucleus broken out of a large solid block yielded plant microfossils. Some of them are suggestive of Cretaceous, others of Miocene age. The suite has been compared with the pollen of 150 modern plants of the Gran Sabana and Roraima Plateau, but they are distinct. Grains and tissue fragments up to 150 microns in size are present, and are considered too big to have been carried by meteoric waters percolating through cracks. Mr. Fournier did not challenge the Precambrian radiometric dating of certain sills which cut the Roraima Formation, but suggested that the formation has accumulated gradually through the whole geologic time, and that careful correlations would show that the polleniferous beds belonged to a higher level. He cited an intrusion of established Triassic age which cuts the basement rocks.
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| Dr. Gordon Young spoke next on the regional setting of the Roraima Formation. By means of regional cross sections from the North Venezuelan coastline to the Amazon Basin, he showed that beds of Roraima type could plausibly be fitted into the paleogeography of several periods. Even age-equivalence, in part, to the Freites Formation would not be a preposterous suggestion. Records indicate that, in a general sense, the Roraima is more indurated and heavily intruded in its lower parts, less so in its higher beds. On this basis a multiple age for the Roraima was suggested.
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| This suite indicates baking of the original shales to temperatures of 400-800°C. [....] Mr. Bowen considered the preservation of pollen in these metamorphosed rocks to be highly unlikely. He therefore favored an external origin, though he could not explain how such contamination took place[.]
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| On opening the meeting to general discussion, several speakers raised the question of how resistant pollen might be to anaerobic baking. It seems that no experiments have been conducted, hence it cannot yet be taken for granted that primary pollen may not occur in hornfelsized shales.
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| Dr. Dallmus supported Dr. Young’s concept of multiple age for the Roraima, and cited known sequences of beds elsewhere in the Brazilian and Colombian Guayana regions, ranging in age from Paleozoic to Tertiary, and cut by flat-lying sills. In contrast Dr. Stainforth claimed that the remarkably horizontal attitude of the Roraima Formation and its sills permitted long-range correlation, and he did not doubt that the hornfelses from Cerro Venamo, Kamarang and Kopinang were correlative and were all altered by intrusion of the underlying Kamarang-Kopinang sill. This sill is dated Precambrian at several localities, and recently the same age was determined for a still higher sill. Thus there is a direct conflict between the radiometric and the palynologic dating.
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[2] http://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/hornfels.html
[3] https://www2.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000207
[4] http://www.britannica.com/EBchecked/topic/377777/metamorphic-rock/80346/Hornfels?anchor=ref751458
[5] http://www.sciences360.com/index.php/hornfels-metamorphic-rocks-created-by-heat-2566/
| The permeability of shales and mudstones determines the effectiveness of seals for many hydrocarbon reservoirs, but measurements are few. Neuzil[5] compiled data sets from 12 laboratory studies and 7 field studies that provided ranges of permeability and porosity data in: Permeability is as high as 1 md in unconsolidated sediment with 70% porosity and as low as 0.01 nanodarcy (nd) in argillite with 5% porosity. With few exceptions, permeability ranges over 3 factors of 10 at a given porosity and decreases progressively as porosity decreases. For example, at a porosity of 20%, permeability ranges from 0.1 μd to 0.1 nd, a range well below the lower limit of k plotted in Fig. 1. Although it was expected that permeability would be scale dependent in clays and shales (regional permeability would be greater than laboratory sample permeability because of fractures), it was found that permeability ranges from the field studies are roughly the same as the laboratory studies, thereby indicating a lack of scale dependence.
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| Thomson[6] describes continental sandstones from the Lower Cretaceous Hosston formation in Mississippi (Fig. 5) : "Secondary quartz cement and compaction through pressure solution of grains are the principal causes of porosity reduction. The early introduction of large amounts of dolomite has inhibited compaction of framework grains. Kaolinite ranges from 5% to 15% of total rock volume. All samples contain a little illite. The permeability/porosity plots indicate a progressive and uniform loss of permeability as porosity is reduced, suggesting that the sandstones underwent a simple diagenetic history, uncomplicated by such late processes as leaching, development of authigenic clay minerals, and so forth." Thomson also suggests that the introduction of hydrocarbons caused a cessation in diagenesis in the lower part of the reservoir. The effect of grain size remains apparent in the data of Fig. 5, although diagenetic effects have blurred the separations seen in Fig. 4, so some of the medium-grained samples have k as low as in the very fine-grained samples.
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[edit] Unknown